What happened
On June 26, 2010, a SeaMax M-22 amphibious ultralight aircraft, registration OH-U567, crashed into the water near Taipalsaari, Finland, during a takeoff attempt. The aircraft, operated for recreational purposes, was being prepared for a flight to Imola. After being stored overnight with its tail partially submerged, the pilot taxied the aircraft into the water.
The first takeoff attempt failed to gain sufficient altitude. During the second attempt, the aircraft failed to reach a normal planing attitude and maintained a tail-heavy posture. The pilot attempted to correct a steep climb angle, but upon reducing engine power, the aircraft experienced a sudden pitch-up movement. The aircraft immediately stalled and plunged into the lake from an altitude of over 20 meters. The pilot, who was the sole occupant, sustained serious injuries, and the aircraft was destroyed.
The investigation
The investigation examined the aircraft's condition, the pilot's experience, and the environmental factors. Investigators found that the aircraft was technically airworthy and the control systems, including the elevator trim, were functional prior to the impact. Video analysis of the flight path revealed a "hooking" motion, similar to a paper glider, before the final stall.
Investigators also looked into the possibility of water accumulation within the fuselage. While the pilot had used the bilge pump briefly before taxiing, the pump was found in the "off" position during the accident. The investigation noted that the aircraft's manual lacked specific instructions on how to effectively remove water from the hull, and there were no sensors to alert the pilot to water ingress.
Findings
- The primary cause of the accident was an unstable center of gravity caused by a significant amount of water accumulated in the rear of the fuselage.
- It is estimated that at least 25 liters of water were required to shift the center of gravity behind the allowable aft limit.
- The pilot had very limited experience with water operations, with only a few hours of floatplane training.
- Environmental conditions included waves of approximately 0.3 meters, which exceeded the manufacturer's recommended takeoff limit of 20 cm.
- Reducing engine power caused a pitch-up moment because the engine is positioned above the center of gravity, which, combined with the aft-shifted weight, led to the loss of control.
Safety action
Following the investigation, the aircraft manufacturer released a technical bulletin and updated the flight and operating manual to provide clearer instructions on water removal. Additionally, the investigation noted that the manufacturer would benefit from implementing a service bulletin system to communicate safety updates directly to owners.